You've listed the max voltage, but you really need a voltage range. I'll just answer about regulators and if someone wants to go beyond my answer, they can.
1) If you have a specific voltage range (e.g 22.2V-25.2V) you can use a linear regulator with a resistor in series. How do you size these? It's just a voltage divider. This is very low efficiency, but depending on your current draw/application, it might be what you need.
V = I*R => P = I^2*R and P = I*V
What's the current of your circuit? That's your I through the regulator.
V_drop = I_reg * R_series (V_drop < (V_min - V_reg))
P_res = I_reg^2*R_series
P_reg = I_reg*(V_bat-V_drop-V_reg)
Make sure you do not dissipate too much power
You have a voltage range of Vbat = [22.2V; 25.2V]
You have a regulator voltage of 3.3V.
You have a 3.3V circuit that draws 170mA.
We want V_drop < (V_min - V_reg)
V_drop < (22.2-3.3)
V_drop < 18.9 (let's say V_drop = 18 to be safe)
V_drop = 18
R = V/I = 18/0.17 = 106 Ohm.
P = I^2*R = 106*.17*.17 = 3W (you could use a bunch of parallel or series resistors for this)
P_reg = (V_bat - V_drop- V_reg)*I
P_reg = (25.2 - 18 - 3.3)*0.17 = 0.663W
Don't really think this is practical....
2) Use a switching regulator. These regulators can take a variety of inputs with a high efficiency and put out a variety of outputs. Be sure to look at the datasheet. The issue with switchers is that they cause higher EMI and you probably want some more filtering.
Here's a decent 1A switcher. Be sure to read the datasheet. I would recommend using a pi-filter on the input to the 3.3V with a cutoff frequency greater than 260kHz with this.